We report a patient who underwent 2-term surgery to treat focal progression of a huge liver metastasis and peritoneal dissemination from a gastric gastrointestinal stromal tumor(GIST)during imatinib mesylate treatment. A 59-year-old man underwent an emergency surgery for perforative peritonitis caused by gastric GIST in June 2006 and a partial resection of the stomach in September 2006. Four years later, abdominal computed tomography(CT)detected a huge liver tumor that occupied the entire right lobe. We initiated imatinib mesylate treatment(400mg/day), and the patient maintained stable disease for several months. However, focal progression of the huge liver tumor and a peritoneal tumor at the splenic hilum were revealed by CT; therefore, an extended right hepatic resection was performed in August 2011 and a distal pancreatectomy, splenectomy, and partial resection of the stomach were performed in February 2012. The patient died of the primary disease at 16 months after the hepatic resection for focal progression.